1. Field
Embodiments of the disclosure relate generally to composite structure, bonded composite structure and composite structure bonded to metal, and more particularly to inspection standard coupons fabricated from such materials having disbonds or delaminations induced by laser generated stress waves.
2. Background
Non-destructive inspection (NDI) standards are required for the calibration of instrumentation used to inspect structures employing composites, bonded composites and metal bonded to composites. The normal method of creation of the standards is to place inserts in the layup of coupons fabricated from composites or within bond interfaces between composite layers or composite and metal layers during manufacture. While these inserts may correctly represent Foreign Object Debris (FOD), they do not represent true disbonds or delaminations. Accordingly, NDI methods can be sensitive to the insert material or effects due to geometry, and not actually be sensitive to a true disbond or delamination. Thus, the inserts may not be correct representations of the desired defect. At edges of the coupon, it is possible to use an insert during bonding and then extract the insert leaving a gap. However, the resulting gap is not of a naturally occurring size and can only represent an edge delamination.
It is therefore desirable to provide a method for creating standards coupons which have naturally appearing disbond or delamination defects for calibration of NDI instrumentation.